The invention relates to a waste pipe system of plastic pipe parts made of thermoplastic material with sound-proofing properties suitable for transporting liquids in waste pipe systems, the inside of the plastic pipe part coming into contact with the liquid.
Such plastic pipe parts made of a substantially plasticizer free polyvinyl chloride with sound-proofing properties for transporting liquids in waste pipe systems is known.
To reduce the noise nuisance, however, the plastic pipe part has to be encased in a sound-proofing layer made of a soft foam plastic having open pores and containing an inorganic filler, the foam plastic having a continuous outer surface.
Such plastic pipe parts present the great disadvantage that the manufacturing costs are very high since, on the one hand, to manufacture it use has to be made of a plastic pipe part manufactured in the normal manner and, on the other hand, use has to be made of a sheathing of foam plastic to be manufactured in a separate step.